The present invention relates to a series of new pyridyloxy derivatives which have the ability to inhibit the secretion of gastric juices and which may thus be used for the treatment and prevention of ulcers. The invention also provides methods and compositions using these new compounds for such treatment and prevention and processes for the preparation of these compounds.
Peptic ulcers are said to occur when there is an imbalance between factors which attack the gastro-intestinal mucosa and factors which defend the gastrointestinal mucosa. The gastric juice is among the attacking factors. Accordingly, if its secretion could be inhibited, this would be useful for the prevention and therapy of ulcers.
Among the drugs so far proposed for the inhibition of gastric juice secretion, anticholinergic agents and histamine-H.sub.2 receptor antagonists (such as cimetidine) have been widely used clinically and have had considerable success, although they are not free from disadvantages. For example, anticholinergic agents have exhibited a range of side effects, including inhibition of movement of the gastrointestinal tract, thirst, mydriasis and inhibition of sweating. Some of the histamine-H.sub.2 receptor antagonists also have undesirable side effects on the central nervous system, and may also have an antagonistic effect on androgens. Moreover, it is thought that the histamine-H.sub.2 receptor antagonists may weaken mucosal protecting factors after long-term administration, and recurrence of ulcers after withdrawal of these drugs has also been observed. Since recurrence is thought to be caused by a decrease in the protecting factors, a drug having the ability both to inhibit gastric juice secretion and to potentiate protecting factor activity would be highly desirable.
We have now discovered that a series of pyridyloxy derivatives having a certain specific and limited class of substituents has the desired combination of gastric juice secretion inhibitory activity, anti-ulcer activity and defense factor potentiating activity, and may therefore be used in the treatment and prevention of gastric ulcers.
A number of compounds having anti-ulcer activity and similar structures to the pyridyloxy derivatives of the present invention is known. Examples include Compound A (disclosed, for example, in European Patent Publication No. 404 949 or WO90/00544), Compound B (disclosed, for example, in Japanese Patent Kokai Application No. Hei-1-193247, Japanese Patent Kokai Application No. Sho-63-225371 and European Patent Publication No. 282 077) and Compound C (disclosed, for example, in Japanese Patent Kokai Application No. Hei-4-257581): ##STR2##
Compound C was disclosed after the priority dates hereof. The compounds of the present invention surprisingly have substantially better activities than these structurally similar and have a combination of gastric juice secretion inhibitory, anti-ulcer and defense factor potentiating activities which these prior compounds do not possess.